Basal metabolic rate and its determinants in postmenopausal women

The basal metabolic rate (BMR) of 70 postmenopausal women (age : 60.6 +/- 4.2yrs., height 154.9 +/- 5.2cm, body weight(BW): 52.7 +/- 6.2kg; mean +/- SD) was evaluated in relation to body composition (body fat mass (FM): 17.3 +/- 3.9kg, lean body mass (LBM): 35.3 +/- 3.6 kg). BMR was 1,148 +/- 126 kcal/day, 21.9 +/- 2.2 kcal/kgBW/day, 32.7 +/- 3.2 kcal/kgLBM/day in all subjects. BMR (kcal/day) significantly correlated with BW (r = .635, p < 0.001) and LBM (r = .598, p < 0.001). When divided into two groups, (lower %fatgroup (LF; < 35%fat) and higher %fat group (HF; greater than or equal to35%fat)), BW and FM were significantly higher in HF than in LF (BW : 56.6 +/- 6.4 vs 51.0 +/- 5.3 kg, FM : 21.7 +/- 2.8 vs 15.5 +/- 2.7kg, p < 0.001, respectively). No difference was observed in LBM between the two groups (34.9 +/- 3.9 vs 35.5 +/- 3.5kg). BMR (kcal/kgBW/day) was lower in HF than in LF (21.0 +/- 1.8 vs 22.3 +/- 2.3, p < 0.05), but HF group had higher BMR in terms of kcal/kgLBM/ day than LF (34.0 +/- 3.1 vs 32.1 coproduct 3.1, p < 0.05). Multiple regression analysis was performed to predict BMR. A single predictor LBM and a pair of predictors LBM and FM explained 35.7% and 42.7% of the variance of BMR. This study suggested that a decrease in LBM is a major factor in affecting the reduction of BMR in postmenopausal women, whereas FM gained after menopause could be considered to have metabolic activity related to BMR.